Rotation resistant friction adapter for plunger driver of drug delivery device

ABSTRACT

A method and system are disclosed for driving a plunger in a drug reservoir. In some embodiments, a variable friction element interconnects between a pushing shaft and a wall of the reservoir. For example, rotation of a driving element in a first direction relative to the pushing shaft may advance the pushing shaft in the reservoir. The friction element may have increased friction resistance to rotation of the pushing shaft in the first direction in comparison to frictional resistance to advancing the pushing shaft. For example, the increased friction may result from wedging a radial element between the pushing shaft and the wall of the reservoir.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to ananti-rotational friction fitting, more particularly, but notexclusively, to a fitting for preventing rotation of a plunger driver ofa drug delivery device.

U.S. Pat. No. 7,967,795 to the present inventor (Oz Cabiri) discloses “acartridge interface assembly including a driving plunger including anouter shaft, and a driver including an inner shaft, the inner shaftmating with an intermediate shaft, the intermediate shaft mating withthe outer shaft, so that the shafts are movable telescopically withrespect to one another, wherein rotation of the driver causes thedriving plunger to advance in a direction away from the driver”.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the invention, there isprovided an assembly for driving a plunger and in a drug reservoir, theplunger dividing between a drug in a distal portion of the reservoir anda proximal opening of the reservoir; the assembly comprising: atelescoping shaft that extends by rotation of a driving element in afirst rotational direction with respect to a distal shaft; a distal endof the distal shaft configured to engage the plunger; and a radialelement extending from the distal shaft to contact an interior side wallof the reservoir, the element configured and oriented to wedge betweenthe interior wall and the distal shaft when the distal shaft is rotatedin the first rotational direction.

According to some embodiments of the invention, the element includes avirtual sprag having a long axis and wherein the long axis intersectsthe interior side wall.

According to some embodiments of the invention, the long axis intersectsthe interior side wall at an angle between 91 and 120 degrees from thefirst rotational direction.

According to some embodiments of the invention, the element includes avirtual beam having a preferred bending direction opposite the firstrotational direction.

According to some embodiments of the invention, the assembly furthercomprises: a plunger interface configured to engage the plunger; theplunger interface irrotationally interconnecting the distal shaft andthe plunger when the plunger interface is engaged to the plunger.

According to some embodiments of the invention, the assembly furthercomprises: a vent for releasing gas from a space between the element andthe plunger.

According to some embodiments of the invention, the radial element islocated proximal to the distal end of the distal shaft.

According to some embodiments of the invention, the wedging islongitudinal such that moving the distal shaft distally with respect tothe reservoir reduces a normal force between the radial element and theinterior wall.

According to some embodiments of the invention, a resistance due tofriction between the radial element and the interior wall to movement ofthe distal shaft in the first rotational direction is higher resistancedue to friction between the radial element and the interior wall tomovement of the distal shaft in a direction opposite the firstrotational direction.

According to some embodiments of the invention, the assembly furthercomprises: a second friction element extending from a drug deliverydevice to contact an exterior side wall of the reservoir when thereservoir is inserted into the drug delivery device, the second frictionelement is configured and oriented to wedge between the exterior walland the reservoir when the reservoir is rotated in a second rotationaldirection.

According to some embodiments of the invention, the second rotationaldirection is opposite the first rotational direction.

According to an aspect of some embodiments of the invention, there isprovided a method of advancing a plunger in a drug reservoir comprising:providing a telescoping assembly that extends by rotating a driver in afirst direction with respect to a pushing shaft mated to the driver, thepushing shaft including a friction element in contact with a wall of thereservoir; rotating the driver in the first direction; wedging thefriction element between the pushing shaft and the wall as result of therotating; inhibiting rotation of the first direction as a result of thewedging; and unwedging the friction element to facilitating advancing ofthe pushing shaft.

According to some embodiments of the invention, the wedging issubstantially the only process impeding rotation of the pushing shaftwith respect to the reservoir.

According to some embodiments of the invention, wedging includeincreasing normal force.

According to some embodiments of the invention, the method furthercomprises: reducing a normal force between the friction element and thewall of the reservoir when the pushing shaft moves in a distaldirection.

According to some embodiments of the invention, the drug reservoirincludes a plunger, the method further comprising: reducing a normalforce between the friction element and the wall of the reservoir whenthe pushing shaft pushes distally against the plunger.

According to an aspect of some embodiments of the invention, there isprovided a drug delivery device comprising: a housing including achannel; a drug reservoir fitting into the channel; and a frictionelement extending from a housing to the channel to contact an exteriorside wall of the reservoir when the reservoir is inserted into thechannel, the element configured and oriented to wedge between theexterior wall and the reservoir when the reservoir is rotated in a firstrotational direction.

According to some embodiments of the invention, the assembly furthercomprises: a telescoping shaft that extends by rotation of a drivingelement in a first rotational direction with respect to a shaft; and asecond friction element inhibiting rotation of the shaft with respect tothe reservoir.

According to some embodiments of the invention, the channel iscylindrical and includes an opening at one end and wherein the reservoirslides longitudinally through the opening into the channel and whereinthe friction element has increased friction resistance to movement inthe first rotational direction than to movement in the longitudinaldirection.

According to an aspect of some embodiments of the invention, there isprovided a method of distributing a drug comprising: supplying areservoir containing the drug and a distribution device including achannel and a friction element; inserting the reservoir intolongitudinally into the channel; and wedging the reservoir against thefriction element by rotating the reservoir with respect to the device.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a flow chart illustration of a method of facilitating movementof a plunger driver in accordance with embodiments of the currentinvention;

FIG. 2 is a flow chart illustration of a method of driving a plunger inaccordance with embodiments of the current invention;

FIG. 3A is a block diagram illustration of an assembly for driving aplunger in accordance with embodiments of the current invention;

FIGS. 3B-3C are schematic diagrams of a sprag element resisting movementin a hindered direction and allowing movement in a direction other thanthe hindered direction in accordance with embodiments of the currentinvention;

FIGS. 4A-4F are drawings of a plunger driving assembly and drugreservoir with a threaded plunger interface in accordance withembodiments of the current invention;

FIG. 5 is a perspective driving of a plunger pushing rod and frictionelement for facilitating forward linear motion in accordance withembodiments of the current invention;

FIGS. 6A-6B are cross sectional views of a plunger pushing rod includingflexible beam anisotropic friction elements in accordance withembodiments of the current invention;

FIGS. 7A-7B are side views of a plunger pushing assembly with reducedfriction when engaged to a plunger in accordance with embodiments of thecurrent invention;

FIG. 8 is a perspective view of a plunger pushing rod including a spragfriction elements and a ram plunger interface in accordance withembodiments of the current invention;

FIG. 9 is a perspective view of a plunger pushing rod including virtualsprag friction elements in accordance with embodiments of the currentinvention;

FIG. 10A is a perspective view of a cartridge including a wheeledfriction element in accordance with an embodiment of the currentinvention;

FIG. 10B is a perspective view of a wheeled friction element with ashaft mount in accordance with an embodiment of the current invention;

FIG. 10C is a perspective view of a wheeled friction element without ashaft mount in accordance with an embodiment of the current invention;

FIG. 11 is a perspective view of a cartridge held by an externalfriction annular element in accordance with an embodiment of the currentinvention;

FIG. 12A is a perspective view of a cartridge including an external semiannular friction element in accordance with an embodiment of the currentinvention; and

FIG. 12B is a perspective view of a cartridge including an external semiannular friction element installed into a drug delivery device inaccordance with an embodiment of the current invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

Overview

The present invention, in some embodiments thereof, relates to ananti-rotational friction fitting, more particularly, but notexclusively, to a fitting for preventing rotation of a plunger driverand/or a reservoir of a drug delivery device.

An aspect of some embodiments of the present invention relates to avariable friction element facilitating forward movement of a plungerpushing shaft inside a drug reservoir. For example, forward motion ofthe pushing shaft may be driven by rotation of a driver element withrespect to the pushing shaft. The friction element may facilitating therelative rotation for example by inhibiting the pushing shaft fromrotating along with the driving element and/or by inhibiting rotation ofthe reservoir. Alternatively or additionally, the friction element maybe designed to reduce friction to forward movement of the pushing shaftand/or reservoir (facilitating movement in the forward, preferreddirection).

In some embodiments, the friction element may facilitate and/or speed upforward movement of the pushing shaft and/or plunger interface prior tocontact with the plunger. Optionally, when the pushing shaft is pushingthe plunger, resistance to forward movement due to the friction elementmay be reduced and/or may self-adjust to minimal and/or may benegligible.

As used herein the term plunger means a piston element. For example, aplunger may include a plunger shaft and/or a plunger head and/or aplunger seal and/or a mating element. As used herein, the term/phraseplunger seal means a piston element that impedes fluid flow. Optionally,plunger seal includes and/or is integral to a piston head. For example,the seal may have the form of a stopper and/or a gasket. In someembodiments, the term plunger may refer to the plunger seal alone. Forexample, the plunger may include a single sealing element that is pushedby a driver. Optionally, the driver may include a pushing shaft.

In some embodiments, the friction element is configured to wedge and/orincrease a normal force between an outer wall of the shaft and an innerwall of the reservoir when the shaft moves in an inhibited directionwith respect to the reservoir. In some embodiments, the friction elementis configured to wedge and/or increase a normal force between an outerwall of the reservoir and a drug delivery device when the reservoirmoves in an inhibited direction with respect to the delivery device.Alternatively or additionally, the friction element is configured tobecome dislodged and/or reduce a normal force between an outer wall ofthe shaft and in inner wall of the reservoir when said shaft moves in apreferred direction with respect to the reservoir. In some embodiments,the preferred direction of movement is in a direction that causes therod to approach the plunger and/or discharge the drug, for exampleadvancement, for example in the distal direction.

In some embodiments, the friction element may include a sprag and/or abeam. For example, a beam may have a preferential mode of bending thatcauses anisotropic friction. Optionally, the sprag and/or beam mayinclude a separate element. Alternatively or additionally, the spragand/or beam may be integral to another element and/or other elements. Asused herein the term virtual element (for example virtual sprag and/orvirtual beam) means an element that is intrinsic to another element. Forexample, a virtual sprag and/or beam may be a region of a radial element(for example the radial element may include a disk) having decreasedcompressibility in comparison to a surrounding region. For example, avirtual sprag and/or beam may include a rib on a radial element.

In some embodiments, a sprag may be an element that is propped betweentwo surfaces at an angle such that a movement of one of the surfaces infirst direction compresses the sprag and/or wedges the sprag between thetwo surfaces thereby increasing a normal force and/or a resistance tothe movement. Alternatively or additionally, movement of the surface ina direction different from the first direction may reduce a normal forceand/or decrease resistance to the movement and/or reducing resistance toanother movement. A virtual and/or a combined sprag may include aportion of an element having properties that cause variable frictionbetween two surface such that a movement in first direction compressesthe sprag increasing resistance to the movement and/or a movement in adirection different from the first direction releases a force on thesprag decreasing resistance to the opposite movement and/or to anymovement. For example, frictional resistance to movement in theinhibited direction may range between 2× to 4× as large and/or between4× to 10× and/or between 10× to 100× or greater than 100× as great asfrictional resistance to movement in an another direction (for examplean opposite direction from the first direction) and/or as frictionalresistance to movement in the preferred direction. For example, movementin the preferred direction may reduce frictional resistance to movementby 2× to 4× and/or by 4× to 10× and/or by 10× to 100× or greater than100×. The combination of increasing frictional resistance to movement ina non-preferred direction while reducing frictional resistance tomovement in a preferred direction may reduce and/or minimize frictionresistance to movement in the preferred direction while increasingand/or maximizing resistance to other movements.

In some embodiments, a friction fitting and/or a plunger interface mayinclude an air vent. The air vent may prevent buildup of an air pocketbetween the plunger interface and the plunger as the pushing shaftand/or plunger interface approaches the plunger.

In some embodiments, the friction element of the present invention maywork with various forms of medicine reservoirs and/or plungers. Forexample, the invention may be configured for a standard syringe,cartridge, reservoir and/or plunger. For example, the cavity of thereservoir may be cylindrical. For example, the cavity of the reservoirmay have smooth walls.

An aspect of some embodiments of the present invention relates to anelement that produces high friction when the pushing shaft is movingwith minimal external resistance and/or produces reduced friction whenthe pushing shaft is pushing against a plunger of the reservoir. Forexample, the plunger interface may be configured to cause the frictionelement to fold and/or bend away from the walls of the reservoir and/orreduce friction when the interface engages the plunger.

In some embodiments, the plunger interface may include a standardconnector. For example, the plunger interface may include a screw thatscrews into the plunger. The interface may transfer linear force and/orrotational torque between the pushing shaft and the plunger.Alternatively or additionally, the interface may transfer linear forcein one or more directions while transferring limited and/or negligibletorque between the pushing shaft and the plunger. For example, a plungerinterface may include a screw thread. Until the screw interface reachesthe plunger, the friction element may inhibit rotation and/or facilitatelinear movement of the pushing shaft. As the screw element engagesbetween the pushing shaft and the plunger, resistance is optionallyadded against forward motion of the pushing shaft and/or the frictioninhibiting rotation of the pushing shaft is optionally reduced.Optionally, the interface and/or the pushing shaft will rotate, engagingthe screw threads. At some point of engagement of the screw threads (forexample when they are fully screwed together and/or fully engaged), theresistance of the plunger to rotation will optionally stop and/or reducerotation of the pushing shaft and/or facilitate further linear advanceof the plunger and/or pushing shaft. Alternatively or additionally, aplunger interface may include a locking element, for example a plug andsocket that transfers torque and/or linear force between the pushingshaft and the plunger. Alternatively or additionally, the plunger mayinclude a ram interface with pushes the plunger without transferringsignificant rotational torque.

In some embodiments, a friction element may be adjusted according thedrive system, injection schedule and/or load on the plunger. Forexample, for a high viscosity payload where the load on the injector ishigh, the friction element may be designed with lower frictionresistance to forward movement. For example, where injection is fast(e.g. for a for a high pitch driving screw) the friction element may bedesigned with lower friction resistance to forward movement. Forexample, for a reservoir having approximately 100 g*cm of torquegenerated pushing the drug during delivery, a friction element may havea torque resistance in an non-preferred direction of approximately 90g*cm and/or a plunger may have a torque resistance of approximately 60g*cm such that the combined torque resistance in the non-preferreddirection of the friction element and plunger may be approximately 150g*cm. More generally, the torque resistance of the friction element in anon-preferred direction may range between 80 to 95% and/or between 65 to80% and/or between 30 to 65% and/or between 5 to 30% and/or between 95to 110% and/or between 110 to 175% and/or between 175 to 300% the torquegenerated by discharging the drug during delivery. The combined torqueresistance in a non-preferred direction of the friction element and theplunger may range for example between 105% to 130% and/or 130% to 170%and/or between 170% to 250% and/or 250% to 500% the torque generated bydischarging the drug during delivery. The torque generated dischargingthe drug during delivery may depend for example on the internal bore ofan injection needle and/or on the cross sectional area of the reservoirand/or on the viscosity of the medicine and/or on a pitch of a drivingscrew. For example, for a 8.65 inner diameter reservoir with a 27G ultrathin wall delivery needle and a drug with viscosity between 30 to 50 cp,and an axial plunger speed of 1-3 cm/min, the axial force dischargingthe drug may be for example in the range between 0.2-3 kgf, the deliverytorque discharging the drug during may range for example between 50-150gr*cm torque on the screw. The combined torque resistance in anon-preferred direction of the friction element and the plunger mayrange for example between 50 to 300*gr·cm. For example as viscosity, thescrew pitch, the cross sectional area increase and/or as the needle borediameter decreases, the delivery torque may increase. Table 1 shows someapproximate exemplary values for delivery torque (for example with an8.65 inner diameter reservoir with a 27G ultra thin wall deliveryneedle). For example, the delivery torque discharging the drug duringmay range between 30 to 45 g*cm and/or between 45 to 70 g*cm and/orbetween 70 to 90 g*cm and/or between 90 to 130 g*cm and/or between 130to 200 g*cm and/or between 200 to 1000 g*cm.

TABLE 1 examples of delivery torque for discharging the drug (notincluding friction of the friction element and the plunger with the wallof the reservoir) Torque Generated While Delivery Viscosity of Drug TSApich 1 cp 30 cp 60 cp 0.75 mm 49.4 g * cm   74 g * cm 123 g * cm 0.85 mm51 g * cm 86.5 g * cm   127 g * cm   1 mm 53 g * cm 86 g * cm 133 g * cm

In some embodiments, tradeoffs are possible. For example, for a higherviscosity drug, a lower pitch driving screw may be used and/or a higherfriction anti-rotational pad may be used with a high pitch screw and/ora larger bore needle may be used. For example, the pitch of a drivingscrew may range between 3 mm to 1 mm and/or between 1 mm to 0.8 mmand/or between 0.8 mm to 0.6 mm and/or between 0.6 mm to 0.3 mm and/orbetween 0.3 mm to 0.2 mm.

In some embodiments, the friction element may be configured to reducefrictional resistance to axial advance of the pushing shaft. Forexample, the normal force between the friction element and the wall ofthe reservoir may be increased by tangential movement and/or decreasedby axial movement. For example, the ratio of normal force duringtangential movement to normal force during axial movement may rangebetween 1.1 to 4 and/or between 4 to 10 and/or between 10 to 100 and/ormore than 100. In some embodiments, the ratio of friction coefficientduring tangential movement to the friction coefficient during axialmovement may range between 1.1 to 4 and/or between 4 to 10 and/orbetween 10 to 100 and/or greater than 100.

In some embodiments, a friction element may include directional frictionsurface, for example micro nails and/or an embossed surface patternand/or slanted hairs and/or scales and/or a non-isotropic molecularstructure etc.

In some embodiments, after advancing in and unengaged state, the shaftmay be engaged to a plunger.

DETAILED EMBODIMENTS

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

Method of Facilitating Preferred Movement of a Plunger Driver

FIG. 1 is a flow chart illustration of a method of facilitating movementof a plunger pushing shaft in accordance with embodiments of the currentinvention. In some embodiments, a friction element may, for example,prevent the pushing shaft from rotating with respect to a reservoirthereby facilitating relative rotation between the pushing shaft and adriver element. Optionally, whenever the pushing shaft begins to rotatein an inhibited direction, friction between the pushing shaft and thereservoir increases. In some embodiments, friction is reduced when thepushing shaft advances. For example, reduction in friction may reduce aload on a drive system while pushing the plunger and/or discharging adrug.

In some embodiments, an immobile medicine reservoir may be supplied 102.For example, the reservoir may have a cylindrical cavity with a distalopening and/or a proximal opening. A plunger is optionally inserted inthe cylindrical cavity. For example, the plunger may divide between adistal portion of the cavity containing the drug and the proximalportion of the cavity.

In some embodiments, a distal portion of a telescoping plunger pushingassembly may be inserted 104 into the proximal opening of the reservoir.For example, the distal portion of a telescoping plunger pushingassembly may include a pushing shaft and/or a distal portion thereof, aplunger interface and/or a friction element. Optionally a plungerinterface of the pushing assembly will engage the plunger when theassembly is inserted 104. Alternatively or additionally, the plungerinterface may remain disengaged from the plunger when the assembly isinserted 104 into the reservoir. In some embodiments, the distal end ofthe pushing assembly may be inserted 104 until it contacts the plunger.Alternatively or additionally, after insertion 104, the distal end ofthe pushing assembly may remain distanced proximally from the plunger.

In some embodiments, a friction surface may be retained 106 in contactwith an interior wall of the reservoir and/or with the pushing shaft.For example, when the system is at rest, a radial element may keep atleast a minimal normal force between the friction surface and theinterior wall of the reservoir. For example, the radial element may beflexible and/or elastically compressible.

In some embodiments, a driving element may be rotated 108 in a firstdirection. Optionally the driving element may be engaged to the pushingshaft. For example, rotation 108 of the driving element may cause thepushing shaft to move 110. For example, the pushing shaft may tend torotate 112 along with the driving element in the first direction. Insome embodiments in may be desired to inhibit rotation 112 of thepushing shaft. For example, when telescoping is driven by relativerotation between the driving element and the pushing shaft, rotation 112of the pushing shaft along with the driving element may be undesirable.Optionally, the friction element may be configured such that rotation112 of the pushing shaft in the first direction wedges 114 the frictionelement and/or the radial element between the pushing shaft and thewalls of the reservoir. Wedging 114 of the friction element between thedriving shaft and the non-rotating reservoir optionally increases anormal force between the friction element and the walls of the reservoirand/or increases friction between the driving shaft and the reservoirand/or inhibits 115 rotation 112 of the pushing shaft.

In some embodiments, a set of screw threads may engage between thedriver element and the pushing shaft. For example, rotation 108 of thedriver element in the first direction with respect to the pushing shaftmay advance 116 the pushing shaft distally into the reservoir. Forexample, advancing 116 may cause the pushing shaft to approach theplunger and/or cause the interface to engage the plunger and/or causethe plunger to advance distally. Optionally, the friction element and/orthe radial element is configured such that advancing 116 the pushingshaft releases 118 a wedged element, for example the friction elementand/or the radial element. Releasing 118 the wedged element optionallydecreases a normal force between the friction element and the walls ofthe reservoir and/or decreases friction between the driving shaft andthe reservoir and/or facilitates 119 advancing of the pushing shaft.

FIG. 2 is a flow chart illustration of a method of driving a plunger inaccordance with embodiments of the current invention. Optionally, theplunger is driven by an advancing pushing shaft. For example, advancingof the pushing shaft may be motivated by relative rotation of a driveelement with respect to a pushing shaft. Tangential friction between afriction element and the reservoir may supply counter rotational torquebetween the pushing shaft and the reservoir, facilitating relativerotation between the pushing shaft and the driver element. In someembodiments, the pushing shaft may advance in the reservoir while thepushing shaft is unengaged to the plunger. Optionally, while the pushingshaft and the plunger are unengaged, the tangential friction between thefriction element and the reservoir may be substantially the only forcepreventing the pushing shaft from rotating along with the rotatingelement. In some embodiments, the friction element may be configured toproduce increased resistance to an undesired movement (for examplerotation with the driving element) and/or decreased resistance to adesired movement (for example advancing of the plunger).

In some embodiments, a distal portion of a plunger pushing assembly maybe inserted 104 into a proximal opening of a drug reservoir. Optionally,the drug reservoir is rotationally immobile. Optionally, the drugreservoir includes a plunger separating between a drug in a distalportion of the reservoir and the proximal opening of the reservoir.Optionally, after insertion, a plunger interface of the pushing assemblymay remain distanced proximally from the plunger. Optionally, theplunger interface is mounted on a distal portion of the pushing shaft.

In some embodiments, after the distal end of the plunger drivingassembly is inserted 104 into the reservoir, a driving element may beengaged 207 to a power source. Alternatively or additionally, thedriving element may be engaged 207 to the power source before beinginsertion 104 of the pushing assembly. For example, the power source mayinclude an electric motor. The power source optionally rotates 108 thedriving element in a first direction.

In some embodiments, during rotation 108 of the driving element in thefirst direction; the pushing shaft may be inhibited 214 from rotating byfriction between a friction element and the inner wall of the reservoir.Optionally, rotation 108 of the driving element in the first directionrelation to a pushing shaft causes the pushing shaft to telescope and/ormove distally with respect to the driving element. For example, thepushing shaft and/or the plunger interface may be advanced 216 distallyuntil it reaches the plunger.

In some embodiments, the plunger interface may engage 232 the plunger.For example, the plunger interface may transfer axial force between theplunger and the pushing shaft. In some embodiments, the plungerinterface may limit rotation between the plunger and the pushing shaft.For example, after engagement of the plunger, friction between theplunger and the interior wall of the reservoir may prevent rotation ofthe pushing shaft in addition to and/or in place of the frictionelement. Alternatively or additionally, the plunger interface may allowrotation of the pushing shaft with respect to the plunger. Optionally,allowing rotation of the pushing shaft with respect to the plunger mayreduce rotational stresses on the plunger.

In some embodiments, when the pushing shaft is advancing and/or when theplunger interface is engaged to the plunger, friction between thefriction element and the wall of the reservoir may be reduced 218.Reducing the friction may make it easier to advance 216 the plungerdriver and/or advance 234 the plunger.

Block Diagram of an Anti-Rotation System

FIG. 3A is a block diagram illustration of a drug reservoir and anassembly for driving a plunger in accordance with embodiments of thecurrent invention. For example, plunger driving assembly may include avariable friction assembly 330 and/or a telescoping assembly including aproximal element 320 and/or a distal shaft 322 and/or a plungerinterface 332. The telescoping assembly optionally telescopes viarotation of proximal element 320 (for example a driver element) withrespect to distal shaft 322 (for example a plunger pushing shaft). Forexample, proximal element 320 may be rotated with respect to a drugreservoir 324 and/or distal element 322 is hindered from rotating withrespect to drug reservoir 324. Optionally, distal element 322 ishindered from rotation by friction with the walls of reservoir 324. Forexample, friction with the walls of drug reservoir 324 may be suppliedby variable friction assembly 330. For example, variable frictionassembly 330 may have high resistance to rotation and/or tangentialmovement with respect to the drug reservoir and/or low resistance toaxial translation with respect to the drug reservoir. Optionally, amotor 321 rotates proximal element 320 with respect to reservoir.

In some embodiments, variable friction assembly 330 may include a radialelement 352 and/or a friction surface 331. Optionally, radial element352 links friction surface 331 to distal shaft 322. Optionally, radialelement 352 retains friction surface 331 in contact with an interiorwall of reservoir 324.

In some embodiments, radial element 352 maintains a variable normalforce between friction surface 331 and the interior wall of reservoir324. For example, radial element 352 may be wedged between the interiorwall of reservoir 324 and shaft 322 such that tangential movement offriction surface 331 in at least one direction causes compression ofradial element (optionally increasing the normal force). Alternativelyor additionally, radial element 352 may be wedged between the interiorwall of reservoir 324 and shaft 322 such that axial movement of frictionsurface 331 in the distal direction causes release of compression ofradial element (optionally decreasing the normal force). For example,the radial element may include one or more of a sprag, a virtual sprag,a beam having a preferred bending direction, a clutch dog, a wedge, aprop and/or a virtual beam having a preferred bending direction.

In some embodiments, radial element 352 may be wedged by movement in anyof a plurality of directions. For example, radial element 352 mayinclude a trapezoidal sprag that is wedged on one side by movement inone direction and on the other side by movement in an oppositedirection. Alternatively or additionally, friction assembly 330 mayinclude multiple anisotropic sprags and/or beams oriented in differentdirections to cause increased friction in more than one direction. Forexample, friction assembly 330 may have increased friction resistance torotation around an axis in both rotational directions and/or havedecreased friction to linear movement in one or more directions.

In some embodiments, friction surface 331 may have an anisotropicfriction coefficient. For example, the friction coefficient may be highin one of the tangential directions optionally causing high frictionresistance to rotation of the distal pushing shaft with respect to thereservoir in at least one direction and/or low friction resistance tomovement distally with respect to the drug reservoir. Alternatively oradditionally, the friction surface may have an isotropic coefficient offriction.

In some embodiments, proximal element 320 may be proximal to, partiallyinserted into and/or fully inserted into a proximal opening reservoir324. In some embodiments, distal shaft 322 may be proximal to, partiallyinserted into and/or fully inserted into a proximal opening reservoir324.

In some embodiments, reservoir 324 may contain a fluid, for example adrug 328. For example, drug 328 may be located in distal portion ofreservoir 324. Optionally a plunger seal 326 may seal off and/orseparate between drug 328 and the proximal opening of the reservoirand/or the plunger pushing assembly.

In some embodiments, when plunger interface 332 is engaged to plungerseal 326 it may supply a one-way, two-way or multi-dimensionalconnection between pushing shaft 322 and plunger seal 326. For example,plunger interface 332 may include a ram that supplies compression forcebetween shaft 322 and plunger seal 326 for pushing plunger distally, butsupplies small and/or negligible tensile force for pulling plunger seal326 proximally. This ram may have friction surface with the plungerand/or partially intrude into the plunger. Alternatively, plungerinterface 332 may include a snap, screw and/or interference element thatsupplies compression force between shaft 322 and plunger seal 326 forpushing plunger distally and also supplies tensile force for pullingplunger seal 326 proximally. In some embodiments, interface 332transmits torque between plunger seal 326 and shaft 322. Alternativelyor additionally, interface 332 may not transmit significant torque; forexample interface 332 may include a pivot that allows shaft 322 torotate independently of plunger seal 326.

FIG. 3B is a schematic diagram of a sprag 353 in accordance with anembodiment of the current invention. For example, in FIGS. 3B and 3C,sprag 353 is in contact with a surface 325. For example, in FIG. 3Bsurface 325 is moving in an inhibited direction indicated by arrow 388.Optionally, when surface 325 is moving in an inhibited direction, theangle of attack 386 between sprag 353 and the direction of movement willbe less than 90 degrees. For example, the angle of attack may rangebetween 89 to 85 degrees and/or between 85 to 70 degrees and/or between70 to 45 degrees and/or between 45 to 0 degrees. Optionally, in someembodiments, a sprag may be anisotropic. For example, an angle of attachmay differ on a leading and/or trailing edge. The movement of surface325 optionally causes a rotational moment 384 on sprag 353 and/or wedgessprag 353 between the outer wall of a shaft 323 and surface 325. Whenmovement is in the inhibited direction, rotational moment 384 and/orwedging optionally produces an increase 382 in the normal force of sprag353 against surface 325. In some embodiments, when movement is in theinhibited direction, rotational moment 384 and/or wedging may produce anincrease a force 383 of friction of sprag 353 against surface 325.

FIG. 3C is a schematic diagram of a sprag 353 in accordance with anembodiment of the current invention. For example, in FIG. 3C surface 325is moving opposite an inhibited direction as indicated by arrow 388′.Optionally, when surface 325 is moving opposite an inhibited direction,the angle of attack 386′ between sprag 353 and the direction of movementwill be greater than 90 degrees. For example, the angle of attack mayrange between 91 to 95 degrees and/or between 95 to 120 degrees and/orbetween 120 to 135 degrees and/or between 135 to 180 degrees. Themovement of surface 325 optionally causes a rotational moment 384′ onsprag 353 and/or releases wedging of sprag 353 between the outer wall ofa shaft 323 and surface 325. When movement is opposite the inhibiteddirection, rotational moment 384′ and/or releasing the wedgingoptionally produces a decrease 382′ in the normal force of sprag 353against surface 325. In some embodiments, when movement is opposite theinhibited direction, rotational moment 384′ and/or releasing the wedgingmay produce a decrease in a force 383′ of friction of sprag 353 againstsurface 325.

Independent Anti-Rotation Sprags

FIGS. 4A-4F are drawings of a plunger driving assembly and drugreservoir with a screw-in plunger interface in accordance withembodiments of the current invention. In some embodiments, a multi spragarm variable anti-rotation friction element 430 may supply rotationalresistance to a pushing shaft (for example see pushing shaft 422 FIG.4B). The anti-rotational friction may facilitate relative rotationand/or telescoping of pushing shaft 422 with respect to a driver (forexample driver 420). For example pushing shaft 422 may be threaded anddriver 420 may include a threaded element, for example a threaded shaftand/or a nut.

FIG. 4A illustrates a plunger driving assembly initially inserted into aproximal opening of a drug reservoir 424 in accordance with anembodiment of the current invention. In some embodiments, distal portionof the plunger driving assembly including for example a plungerinterface 432 and/or variable resistance friction element 430 and/or adistal portion of pushing shaft 422. Optionally, when the plungerdriving assembly is inserted, a plunger interface 432 remains distal toand/or disengaged from a plunger seal 426.

In some embodiments, a transmission gear 444, driver 420, a needleretraction lock 446 and a part of the proximal shaft 422 are locatedoutside and/or proximal to reservoir 424. Optionally, the distal end ofreservoir 424 includes a distal opening and a needle mount 442. Thedistal opening is optionally connected to a hypodermic needle 436.Optionally, the distal portion of reservoir 424 is filled with a drug228. Plunger seal 426 separates and/or seals reservoir 424 betweenmedicine 228 and a proximal portion and/or the proximal opening of thereservoir.

FIG. 4B illustrates a plunger driving assembly with the telescopingassembly beginning to open, advancing plunger interface 432 towardsplunger seal 426 in accordance with an embodiment of the currentinvention. In some embodiments, after insertion, the telescopingassembly may be extended to advance interface 432 toward plunger seal426 and/or to engage interface 432 to plunger seal 426.

In some embodiments, interface 432 is advanced by rotating transmission444 and/or retraction lock 446 and/or driver 420 with respect toreservoir 424. Driver 420 is optionally threadably engaged to pushingshaft 422. In some embodiments, friction between friction element 430and the inner walls of reservoir 424 inhibits rotation of pushing shaft422 such that rotating driver 420 results in relative rotation betweendriver 420 and pushing shaft 422. Relative rotation of driver 420 andpushing shaft 422 optionally advances pushing shaft 422 and/or interface432 towards plunger seal 426.

In some embodiments, interface 432 advances until it contacts plungerseal 426. When interface 432 contacts plunger seal 426, interface 432may become linearly linked to plunger seal 426 (for example in thatfurther linear advancement of interface 432 advances plunger seal 426)and rotationally independent of plunger seal 426 (in that rotation ofinterface 432 does not rotate plunger seal 426). In some embodiments,distal advancement optionally stops due to the normal force betweeninterface 432 and plunger seal 426 and/or friction force between plungerseal 426 and the walls of reservoir 424 and/or the normal forces betweendrug 228 and plunger seal 426. Optionally, rotation of driver 420 whileinterface 432 does not advance overcomes friction between frictionelement 430 and the walls of reservoir 424 and/or causes rotation ofinterface 432. For example, rotation of interface 432 may screw it intoplunger seal 426.

In some embodiments, when interface 432 is fully screwed into plungerseal 426, interface 432 becomes rotationally linked to plunger seal 426(for example in that further rotation of interface 432 rotates plungerseal 426). In some embodiments, rotation of interface 432 optionallystops due to the combined frictional resistance to rotation of interface432 and plunger seal 426 with respect to the walls of reservoir 424.Optionally, rotation of driver 420 while interface 432 does not rotateovercomes resistance to axial motion and/or plunger seal 426 begins tomove axially and/or discharges the drug from the distal opening of thereservoir (for example through needle 436). In some embodiments,reservoir 424 may include a flange 438. For example, flange 438 mayextend out from a rear portion of reservoir 424.

FIG. 4C is a close up perspective view of a distal end of a pushingshaft including a plunger interface 432 and a friction element 430 inaccordance with an embodiment of the current invention. In someembodiments, an anti-rotation assembly may include a vent 450. Forexample, vent 450 may allow air to escape the zone between plunger seal426 and interface 432 for example as interface 432 approaches plungerseal 426.

In some embodiments, a stabilizing base 440 may limit proximal movementof friction element 430 and/or determine the axial relationship ofinterface 432 and/or shaft 422 to friction element 430 and/or directbowing and/or buckling of a radial element 452. For example, base 440prevents radial elements 452 from buckling proximally and/or disengagingfrom the walls of reservoir 424. Optionally, there is a friction surface431 on an external end of at least on radial element 452. For example,friction surface 431 may be held in contact with an interior wall of thereservoir.

FIG. 4D is a close up perspective view of a friction element 430 inaccordance with an embodiment of the current invention. For example,element 430 is optionally a flexible disk shaped element withindependent flexible radial elements 452, for example sprags.Optionally, each sprag includes a friction surface 431 for contactingthe walls of reservoir 424. For example, each sprag is tilted off theradial direction towards the direction of inhibited movement.Optionally, friction surface 431 is on the outer end of the each radialelement 452. For example, the outer end of each radial element 452spread as it radiates outward and/or the outer end (head 453) of eachsprag may be wider than its central end (stem 455).

In some embodiments, radial elements 452 are angled against an inhibiteddirection of rotation. For example, the inhibited direction of rotationmay be the direction of rotation of driver 420 for extension of thetelescoping assembly. Optionally, when driver 420 is rotating in adirection to expand the telescoping assembly (and/or advance pushingshaft 422) and frictional element 430 begins to rotate in the directionof rotation of driver 420, sprag type radial elements 452 get wedgedagainst the walls of reservoir 424. Optionally, when driver 420 isrotating in a direction to expand the telescoping assembly (and/oradvance pushing shaft 422) and frictional element 430 begins to rotatein the direction of rotation of driver 420 friction is increase betweenfrictional element and reservoir 424 inhibiting the rotation of shaft422 and/or facilitating relative rotation between driver 420 and shaft422 and/or facilitating advancement of shaft 422. In some embodiments, asprag 452 may be anisotropic. For example, the angle of attack of aleading edge 456 a may be steeper than the angle of attack of a trailingedge 456 b. For example, the mean angle of attack of sprag 452 may rangebetween 80 and 90 degrees while the mean difference between the leading456 a and trailing 456 b edges may range between 1 and 9 degrees. Forexample, the mean angle of attack of a sprag may range between 60 and 80degrees while the mean difference between the leading and trailing edgesmay range between 1 and 40 degrees. For example, the mean angle ofattack of a sprag may range between 20 and 60 degrees while the meandifference between the leading and trailing edges may range between 1and 70 degrees.

In some embodiments, friction element 430 may be made of rubber,elastomer and/or silicone for example of hardness shore 00 scaleapproximately 50. For example, the hardness may range between shore 00scale 10 to 30 and/or 40 to 60 and/or 60 to 100 and/or shore A scale 60to 100. Optionally, the unstressed diameter of friction element 430 isslightly larger than the inner diameter of reservoir 424. For example,the unstressed outer diameter of element 430 may be approximately 9.1 mmwhile the inner diameter of reservoir 424 may be approximately 8.65 mm.Optionally, the inner diameter of a reservoir may range between 1 to 4mm and/or between 4 to 7 mm and/or between 7 to 10 mm and/or between 10to 15 mm and/or between 15 to 30 mm. Optionally, the outer diameter of afriction element may range between 100% to 103% and/or 103% to 107%and/or 107% to 120% and/or 120% to 150% the internal diameter of thereservoir. In some embodiments, friction element 430 may have a closeddiameter at the base (stem 455) of sprags 452 of approximately 6.3 mmand/or the length of sprags 452 (in the radial direction) may beapproximately 1.4 mm. For example, the thickness (along the length ofreservoir 424) of element 430 and/or sprags 452 may be 2 mm and/orradial length of the head of sprags 452 may be approximately 1.65 mmand/or the surface 431 area of each sprag 452 in contact with the innerwall of reservoir 452 may be approximately 2+1.65=3.3 mm². In someembodiments, the length of a sprag element may range for example between1 and 10% the diameter of the reservoir and/or between 10 to 20% thediameter of the reservoir and/or between 20 to 40% the diameter of thereservoir and/or between 40 to 70% the diameter of the reservoir and/orbetween 70 to 100% the diameter of the reservoir. In some embodiments,the width of a friction element may range for example between 1 to 5%and/or between 5 to 15% and/or between 15 to 25% and/or between 25 to50% and/or between 50 to 75% and/or between 75 to 150% and/or between150 to 600% the diameter of the friction element.

In some embodiments, friction element 430 may include a mount forconnection to pushing shaft 422 and/or to interface 432. For example,shaft mount 454 of friction element 430 includes an internally threadedaperture that threadably mates to an external threads 462 of plungerinterface 432 (see for example FIG. 4E).

FIG. 4E is a close up perspective view of plunger interface 432 inaccordance with an embodiment of the current invention. For example,interface 432 is optionally a hard element (for example made of moldedplastic) with a tapered screw thread 462 for attaching to plunger seal426 and/or friction element 430. Optionally, interface 432 includes atapered distal face 466 and/or a proximal base 440 and/or a vent 450.Optionally vent 450 includes a slit in base 440. Optionally, slit 450 ispositioned to align with a space between radial elements 452.Alternatively or additionally, a friction element may include a vent.For example, when the friction element is mounted on interface 432, thevent of the friction element may be aligned with vent 450.

In some embodiments, friction element 430 may include a mount forconnection to pushing shaft 422 and/or to interface 432. For example,shaft mount 454 of friction element 430 includes an internally threadedaperture that threadably mates to an external threads 462 of plungerinterface 432 (see for example FIG. 4E).

FIG. 4F is a cross sectional view of friction element 430 mounted on anadapter 432 in accordance with an embodiment of the present invention.For example, screw threads 462 are smaller at the insertion point (thedistal end) and grow as one moves proximally. The rear (proximal) faceof the teeth is optionally at a sharper angle (for example between 70 to95 degrees from the axis of adaptor 432) than the front (distal) face ofthe teeth (which range for example at an angle between 115 to 145degrees from the axis of adaptor 432).

Linear Motion Sensitive Sprags

FIG. 5 is a perspective drawing of a plunger pushing rod and frictionelement for facilitating forward linear motion in accordance withembodiments of the current invention. Optionally, friction element 530is angled backwards (for example proximally). For example, advancementof shaft 422 the angle of attack of element 530 would be greater than 90degrees. Optionally, advancement of shaft would reduce the normal forceand/or the friction between friction element 530 and the wall areservoir 424. Optionally, when shaft 422 is rotating but not advancing,the friction between element 530 and reservoir 424 is high, inhibitingrotation. Optionally, as shaft 422 advances in reservoir 424, the shapeof element 530 causes a reduction in friction facilitating theadvancement.

Friction Disk with Anti-Rotation Beam

FIG. 6A is cross sectional view of a plunger pushing rod includingflexible beam anisotropic friction elements in accordance withembodiments of the current invention. In some embodiments, a frictionelement 630 may include an anisotropic bending beam 652. For example,when beam 652 is bent in an inhibited direction it may not bend awayand/or it may get wedged between a plunger interface 632 and the wallsof reservoir 424. For example, when beam 652 is bent in a non-inhibiteddirection, beam 652 may bend out of the way and/or reduce friction. InFIG. 6A elements 652 are illustrated in a relatively unstressed state.

In some embodiments, a beam may have anisotropic compressibility and/orextensibility. For example, beam 652 has a cut out section 672. The sideof the beam with the cut out extends and/or compresses more easily thanthe opposite side.

FIG. 6B illustrates element 652 in a stressed state due to rotation ofinterface 632 in an inhibited direction 678 in accordance with anembodiment of the present invention. Optionally, when element 652 isstressed, cut out section 672 may tend to expand and/or contract whileuncut side of the beam may tend to buckle and/or bend. Optionally,stress due to rotation in the inhibited direction 678 causes cut outsection 672 to open wedging surface 631 against reservoir 424 increasinga normal force and/or a friction between surface 631 and reservoir 424.

Pressure Sensitive Friction Element

FIGS. 7A-7B are side views of a plunger pushing assembly with reducedfriction when engaged to a plunger in accordance with embodiments of thecurrent invention. For example, a friction element 730 may be sized tocontact a wall of a drug reservoir and/or produce friction with the wallinhibiting rotation of a plunger pushing shaft 422 and/or a plungerinterface 732. Optionally, when interface 732 engages a plunger 726,friction between element 730 and the reservoir may be reduced and/or theresistance to advancement of the plunger may be reduced.

FIG. 7A illustrates plunger interface 732 and friction element 730 whiledisengaged from a plunger in accordance with an embodiment of thecurrent invention. In some embodiments, shaft 422 may be advancedthrough reservoir 424 by rotation of a driver relative to shaft 422. Asinterface 732 approaches plunger 726, friction element contacts theinterior walls of reservoir 424 and/or inhibits rotation of shaft 422and/or facilitates the relative rotation of the driver with respect toshaft 422.

FIG. 7B illustrates plunger interface 732 and friction element 730 whileengaged to a plunger in accordance with an embodiment of the currentinvention. In some embodiments, when interface 732 engages plunger 726,an element (for example the hard side walls of the plunger and or a bowlshaped and/or annular projection) deform friction element 730.Deformation of friction element 730 optionally reduces and/or eliminatescontact between friction element and reservoir 424. For example,deformation of friction element 730 may reduce and/or substantiallynullify friction between element 730 and reservoir 424. Optionally, whenplunger interface 732 is engaged with plunger 726, friction betweenplunger 726 and reservoir 424 may inhibit rotation of shaft 422 and/orfacilitate advance of shaft 422 and/or plunger 726. In some embodiments,reduction of the friction between element 730 and reservoir 424 mayreduce the load on a plunger pushing assembly. For example, interface732 may be engaged to plunger 726 while a device is discharging a drug.Reduction of friction between element 732 and reservoir 424 optionallyreduces the load on the plunger pushing system while discharging thedrug.

In some embodiments, advancement of the plunger pushing assembly mayproceed through a few friction stages and/or configurations. Forexample, while interface 732 is distanced proximally from plunger 726,the resistance to rotation caused friction between element 730 andreservoir 424 may be enough to prevent rotation of shaft 422. With shaft422 rotationally immobile, rotation of a driver may produce relativerotation between the driver and shaft 422 and/or advancement of shaft422.

In some embodiments, shaft 422 advances until interface 732 contacts theproximal side of plunger 726. Once interface 732 contacts the proximalside of plunger 726 rotation of the driver and resistance to rotation byfriction element 730 may be enough to overcome resistance to advance ofplunger 726. Subsequently, interface 732 is driven forward, drivingforward plunger 726 and discharging the medicine. Alternatively oradditionally, when interface 732 contacts the proximal side of plunger726, resistance to advance of plunger 726 may be enough to stop advanceof shaft 422. While resistance of plunger 726 prevents advance ofinterface 732, torque optionally overcomes rotation resistance ofelement 730. For example, overcoming rotational resistance may causeinterface 732 to rotate and/or be screwed into the proximal end ofplunger 726 and/or engage plunger 726.

In some embodiments, once interface 732 is engagement of interface 732to plunger 726 may prevent rotation of interface 732 with respect toplunger 726. Friction between plunger 726 and reservoir 424 may preventfurther rotation of shaft 422, facilitating relative rotation of shaft422. Prevent rotation of interface 732 optionally facilitates rotation adriver in relation to shaft 422 optionally facilitating further advanceof plunger seal 426.

Plunger Interface

FIG. 8 is a perspective view of a plunger pushing rod including a spragfriction elements and a ram plunger interface in accordance withembodiments of the current invention. In some embodiments, a plungerinterface will transfer linear forces between a plunger and a pushingshaft 422. Optionally, the interface will transfer limited or negligiblerotational torque between the plunger and the pushing rod. For example,a ram 832 may push a plunger along an axis of a drug reservoir (forexample distally). Ram 832 may transfer little or no torque around theaxis. For example, embodiments, ram 832 may not be rotationally fixed toshaft 422 and/or to the plunger. Torque is optionally transferredbetween shaft 422 and the plunger by friction. Alternatively oradditionally, there may be a rotating element (for example a pivotand/or an axel) between shaft 422 and ram 832 limiting transfer oftorque. Optionally, rotational resistance of friction element 830 willbe high enough to prevent a driver from rotating shaft 422 under thedual load of linear resistance of friction element 830 and the plunger(resistance to linear movement of the plunger may include for examplefriction between the plunger and the reservoir and/or resistance todischarge of the drug).

Friction Disk with Anti-Rotation Sprag Ribs

FIG. 9 is a perspective view of a friction element 930 including virtualsprag friction elements in accordance with embodiments of the currentinvention. In some embodiments, a radial element 952 may be constructedof angled layers of connected sheets 992. Sheets 992 are optionallyangled toward the inhibited direction 996 of rotation. When theperiphery of element 930 are in frictional contact with an immobilereservoir wall, rotation of element 930 in the inhibited direction 996optionally spreads sheets 992 and/or increase a surface area offriction. Alternatively or additionally, rotation in the inhibiteddirection 996 pushes against joints 994 which are virtual sprag elementsthat are optionally stiffer than the sheets, for example increasing anormal force between friction element 930 and a wall of a reservoir.Alternatively or additionally, virtual sprag elements may include athickened rib angled against the inhibited direction and/or a rib of astiffer material than the rest of the disk angled against the directionof inhibited movement. Optionally, friction element 930 optionallyincludes a shaft mount 954.

Friction Element with Rollers

FIG. 10A is a perspective view of a friction element 1030 a includingrolling element 1051 in accordance with embodiments of the currentinvention. For motion in the preferred direction, rolling element 1051may roll, allowing motion with minimal friction whereas for motion inthe non-preferred direction. For example, friction element 1030 a maymove axially inside reservoir 424 with a friction force of a hundredthor less than the force necessary to rotate element 1030 a around theaxis of reservoir 424. For example, a rolling element may be roundand/or spherical and/or cylindrical and/or tapered. A rolling elementmay include a wheel and/or an axel and/or a bearing and/or a race and/ora cage.

In some embodiments, for example as illustrated in FIG. 10B, rollingelement 1051 may include a wheel 1052. For example, during movement in apreferred direction, for example as element 1030 b moves linearly alongthe axis of reservoir 424, wheel 1052 may rotate around an axel 1055.Optionally, a rolling element may be inside an indentation and/or a ballcage 1091. For example, cage 1091 optionally includes an indentation ina connecting element 1089 b. For example, connecting element 1089 b mayinclude a disk and/or cylindrical connector between a drive screw and/ora plunger adapter. Alternatively or additionally, friction element maybe built into a driving element and/or a plunger adapter. For example, awheel and/or an axel and/or a race and/or a cage may be built into theplunger adapter and/or the drive element.

Some embodiments of an anti-rotational element 1030 b, a connectingelement 1089 b may include a shaft mount 1054, for example asillustrated in FIG. 10B. Additionally or alternatively, in someembodiments of an anti-friction element 1030 c, a connecting element1089 c may not have a shaft mount, for example as illustrated in FIG.10C. For example, connecting element fit between a driving shaft and/ora plunger.

Friction Element Preventing Rotation of Reservoir

FIG. 11 is a perspective view illustration of a drug reservoir with anexternal anti-rotational friction element in accordance with anembodiment of the present invention. Optionally, an external frictionelement 1130 resists rotation of the reservoir with respect to a housingof a drug delivery device. For example, friction element 1130 hasanisotropic friction with higher frictional resistance against movementin a non-preferred direction than in a preferred direction. For example,sprags 452 have enhanced friction to resist rotation of reservoir 1124in a non-preferred direction. Optionally, reservoir can easily be slidlongitudinally into element 1130, but once in place is difficult to movein a non-preferred direction (for example to rotate against sprags 452and/or to remove reservoir 1124).

In some embodiments, element 1130 may have the form of a ringsurrounding reservoir 1124. Optionally, sprags 452 radiate inward fromthe ring towards the outer wall of reservoir 1124.

In some embodiments, a system may include two directionally preferentialfriction elements. For example, friction element 430 may preventrotation of a plunger driving shaft. For example, element 430facilitates movement of a plunger driver by a shaft driver 1120. In someembodiments, sprags 452 of internal friction element 430 are oriented inthe opposite direction from sprags 452 of external friction element1130. For example, friction element 430 may prevent a plunger driverfrom rotating by applying a first torque in a first non-preferreddirection (non-preferred with reference to inner element 430) to aninner wall of reservoir 1124. Optionally, element 1130 may preventrotation of reservoir 1124 by providing an opposite torque to the outerwall of reservoir 1124. The second torque may inhibit rotation ofreservoir 1124 in a second non-preferred direction. In some embodiments,the first and second non-preferred directions may be opposite inorientation.

In some embodiments, external friction element 1130 may include anchors1157 to hold it in a drug delivery device. For example, anchors 1157 areprotrusions molded into element 1130 that fit into indentations on theinner wall of a casing of a drug delivery device (for example casing1259 as illustrated in FIG. 12B). Optionally, anchors 1157 inhibitmovement of element 1130 with respect to the drug delivery device.Optionally, other means may be used to stabilize element 1130 withrespect to a delivery device, for example glue and/or other sorts ofanchors and/or fittings.

FIG. 12A is a perspective view illustration of a drug reservoir with analternative external anti-rotational friction element 1230 in accordancewith an embodiment of the present invention. Optionally, element 1230only partially surrounds reservoir 1124. Element 1230 is optionallymolded in one step with other elements of a drug delivery device. Forexample, element 1230 includes an elastomeric button cover 1257 for thedelivery device.

FIG. 12B illustrates an internal view of friction element 1230 installedinto a top half of a casing 1259 of a drug delivery device. Element 1230optionally serves to inhibit rotation of reservoir 1124. Optionally,cover 1257 seals a hole in casing 1259 providing a water tight seal. Thehole optionally provides access for a user to push an activation buttonof the device.

Optionally, an outer friction element may include various anisotropicfriction elements as described herein above for example a sprag and/oran anisotropically bending beam and/or a clutch dog and/or a virtualelement and/or an anisotropic friction surface. Friction to inhibitrotation of the reservoir may optionally be provided by multipleelements.

Exemplary Dimensions of a Drug Delivery Device

In some embodiments, the payload of a reservoir (for example a syringe)may include, for example between 0.5 and 2 ml and/or between 2 and 4 mland/or between 4 and 5 ml of a drug and/or more. In some embodiments,the injector may discharge the entire payload as a single dose. A drugdelivery device may include, for example, a pen injector, and/or aninternally powered driver to drive the plunger and/or discharge thepayload. For the sake of this application, an internally poweredinjector driver may be defined as a drive mechanism powered by energystored at least temporarily within the injector. Power may be stored ina power supply, for instance as chemical potential (for example achemical that produces an expanding gas and/or a battery) and/ormechanical potential (for example stored in an elastic member and/or aspring and/or torque spring and/or a pressurized gas). For example, thedriver may be designed to discharge the payload over a time periodranging between 20 and 120 seconds and/or between 120 and 600 secondsand/or longer. In some embodiments, discharge may be driven by a driver.An internally powered driver may be powered by various mechanismsincluding for example a motor (including for example a DC motor, anactuator, a brushless motor) and/or a transmission including for examplea telescoping assembly and/or a threaded element and/or a gear and/or acoupling and/or an elastic mechanism (for example a spring and/or arubber band) and/or an expanding gas and/or a hydraulic actuator).

A drug delivery device in accordance with some embodiments of thecurrent invention may include reservoir. For example, a reservoir mayinclude a medicine container and/or a standard type syringe. Optionally,a standard type syringe may be preloaded with medicine using standardequipment and/or in an aseptic room. A preloaded standard type syringemay optionally include a proximal opening. A plunger may optionally sealthe proximal opening and/or protect the sterility of the contents of thesyringe. A sterile needle (for example a hollow needle) may optionallybe connected to the syringe barrel. For example, the hollow of theneedle may be in fluid communication with the interior of the barrel.The needle may optionally be rigidly attached to the distal end of thebarrel. The sterility of all and/or part of the needle may for examplebe protected by a sterile cover. The sterile cover may remain on theneedle when the syringe is supplied and/or installed into an injector.For example, the medicine container may optionally include a cylindricalbarrel rigidly attached to a needle. Optionally, the long axes of theneedle and barrel of the syringe may be parallel and/or coaxial.Optionally, the needle may be mounted on the distal end of the barrel.Optionally, the needle point may be pointing in the distal direction. Insome embodiments, a plunger may slide axially along the inside of thebarrel to discharge a medicine payload. For example, the medicine may bedischarged through the hollow needle.

In some embodiments, the force to insert the needle to the skin of apatient may range for example between 0.02 to 0.2 N and/or between 0.2and 0.5 N. Optionally, the force required to inject the drug (forexample the force on a syringe plunger) may range for example between 5to 60 N. For example, the force required to inject the drug may dependon the injection rate and/or the viscosity of the drug and/or thesyringe geometry and/or the needle dimensions.

For example, in the event of an occlusion and/or at the end of delivery,the linear force generated by the device may increase to the level of upto 60 N. A needle safeguarding mechanism (for example a needleretraction mechanism) may be sensitive to the force. For example,mechanism may include a snap that gives way at 40 N returning the needleto the retracted position. In some embodiments, a needle protectionmechanism may be triggered by a linear force greater than, for example,between 10 to 60 N.

In some embodiments, the stress to inject a medicine and/or to triggersafeguarding of a needle may include a torque. For example, injection ofmedicine may be driven by a plunger. The plunger may optionally bedriven by a threaded assembly, for example a threaded screw and/or teethand/or a telescoping assembly. Optionally, the pitch of the teeth and/oran associated screw may range for example between 0.5 and 2 mm. Thediameter of the screw may range for example between 3 and 15 mm. Thetorque to power injection may range for example between 0.2 and 1.0N*cm. The trigger torque (the torque at which the needle safeguarding istriggered) may range for example between to 0.5 to 2 and/or from 2 to 4and/or from 4 to 10N*cm.

During injection, the linear movement of a plunger may range for examplebetween 10-50 mm. The length of movement of the plunger may vary forexample with the volume of medicine to be injected that may range forexample between 0.5 to 3 ml.

In some embodiments, discharge may be driven by a torque. For example,the driver may apply torque to threaded element pushing a plunger. Insome embodiments, a time of discharge may depend on the fill volumeand/or viscosity. For example, the expected injection speeds may beInjection speed depend on viscosity, for example for viscosity rangingfrom 1 cp to 15 cp the expected injection rage may range between 30 to40 sec/1 ml, for example for viscosity ranging from 15 cp to 60 cp theexpected injection rate may range between 35 to 60 sec/ml for viscosityabove 60 cp the expected injection rate may range between 53 to 67 sec/1ml. The maximum and/or minimum expected injection time may for examplebe the maximum and/or minimum allowed fill volume divided by aninjection rate. For example an expected time of discharge may range forexample between 24 to 48 seconds (for example for between 0.8 and 1.2 mlof fluid having a viscosity ranging between 1 to 15 cp) and/or between36 to 68 seconds (for example for between 1.2 and 1.7 ml of fluid havinga viscosity ranging between 1 to 15 cp) and/or between 51 to 92 seconds(for example for between 1.7 and 2.3 ml of fluid having a viscositybetween 1 to 15 cp) and/or between 70 to 150 seconds (for example for2.0 to 2.5 ml of fluid having a viscosity of between 15 and 40 cp)and/or between 120 seconds and 3 minutes for larger volumes and/orviscosities.

In some embodiments, the drug delivery device may be configured tooperate independently and/or be handheld. For example, the device mayhave a weight ranging between 10 grams to 30 grams and/or between 30grams to 150 grams and/or between 150 grams to 500 grams. Optionally,the drug may be contained within the device. Optionally, the fluid pathof the drug from the reservoir to the injection needle may be within thedevice. Optionally, the power supply may be within the device.Optionally, the device may be operable with one hand.

It is expected that during the life of a patent maturing from thisapplication many relevant technologies will be developed and the scopeof the terms are intended to include all such new technologies a priori.

As used herein the term “about” refers to ±5%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. An assembly for driving a plunger in a drugreservoir, the plunger dividing between a drug in a distal portion ofthe reservoir and a proximal opening of the reservoir; the assemblycomprising: a telescoping shaft that extends by rotation of a drivingelement in a first rotational direction with respect to a distal shaft;a distal end of said distal shaft configured to engage the plunger; andan anisotropic friction element extending from said distal shaft, saidfriction element comprising a disk and a plurality of independent radialelements extending radially from the disk to contact an interior sidewall of the reservoir, said radial elements extending from the disktoward the first rotational direction to wedge between said interiorwall and said distal shaft when said distal shaft is rotated in saidfirst rotational direction, said radial elements having respectiveleading edges and trailing edges, at least one of the leading edgesextending radially from the disk at a first angle and a trailing edgeassociated with a same radial element as the at least one of the leadingedges extending radially from the disk at a second angle, the firstangle being steeper than the second angle.
 2. The assembly of claim 1,wherein each radial element includes a virtual sprag having a long axisand wherein said long axis intersects said interior side wall.
 3. Theassembly of claim 1, further comprising: a plunger interface configuredto engage the plunger; said plunger interface rotationally linking saiddistal shaft and the plunger when said plunger interface is engaged tothe plunger.
 4. The assembly of claim 1, further comprising: a vent forreleasing gas from a space between the friction element and the plunger.5. The assembly of claim 1, wherein said friction element is locatedproximal to said distal end of said distal shaft.
 6. The assembly ofclaim 1, wherein said wedging is longitudinal such that moving saiddistal shaft distally with respect to said reservoir reduces a normalforce between said friction element and said interior wall.
 7. Theassembly of claim 1, wherein a resistance to movement of said distalshaft in said first rotational direction due to friction between saidfriction element and said interior wall is higher than a resistance tomovement of said distal shaft in a direction opposite said firstrotational direction due to friction between said friction element andsaid interior wall.
 8. The assembly of claim 1, further comprising: asecond friction element extending from a drug delivery device to contactan exterior side wall of the reservoir when said reservoir is insertedinto said drug delivery device, said second friction element isconfigured and oriented to wedge between said exterior wall and saidreservoir when said reservoir is rotated in a second rotationaldirection.
 9. The assembly of claim 8, wherein said second rotationaldirection is opposite said first rotational direction.
 10. The assemblyof claim 1, wherein each radial element defines a radially central endand a radially outer end, the radially outer end of at least one radialelement being wider than the corresponding radially central end thereof.11. A method of advancing a plunger in a drug reservoir comprising:Providing a telescoping assembly that extends by rotating a driver in afirst rotational direction with respect to a pushing shaft mated to thedriver, said pushing shaft including an anisotropic friction element incontact with a wall of the reservoir, said friction element comprising adisk and a plurality of independent radial elements extending radiallyfrom the disk, said radial elements having respective leading edges andtrailing edges, at least one of the leading edges extending radiallyfrom the disk at a first angle and a trailing edge associated with asame radial element as the at least one of the leading edges extendingradially from the disk at a second angle, the first angle being steeperthan the second angle; rotating said driver in said first rotationaldirection; wedging said friction element between said pushing shaft andsaid wall as result of said rotating; inhibiting rotation of saidpushing shaft as a result of said wedging; and unwedging said frictionelement to facilitate advancing of said pushing shaft.
 12. The method ofclaim 11, wherein said wedging is substantially the only inhibiting ofrotation of said pushing shaft with respect to the reservoir.
 13. Themethod of claim 11, wherein said wedging increases a force normal tosaid wall and said pushing shaft relative to the normal force prior tothe wedging.
 14. The method of claim 12, further comprising: reducing anormal force between said friction element and said wall of thereservoir when said pushing shaft moves in a distal direction.
 15. Themethod of claim 11, wherein the drug reservoir includes a plunger, themethod further comprising: reducing a normal force between said frictionelement and said wall of the reservoir when said pushing shaft pushesdistally against said plunger.